Aircraft personnel trainer



Feb. 1, 1949. c. E. GERMANTON AIRCRAFT PERSONNEL TRAINER 4 Sheets-Sheet2 Filed June 30, 1944 kan Pa'tented Feb. 1, 1949 UNITED STATES PATENTOFFICE AIRCRAFT PERSONNEL TRAINER Charles E. Germanton, Summit, N. J.,assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y.,a corporation of New York Application June 30, 1944, Serial No. 542,982

This invention relates to aircraft trainers and more particularly toapparatus for simulating ln the operation of the controls the reactionswhich a pilot would receive in the operation of an actual aircraft dueto the encountering of rough air conditions.

In the control of an aircraft the pilot feels resistance to theoperation of the stick or yoke, of the aileron wheel if providedseparate from the yoke, and of the rudder pedals, which varies inaccordance with the pressure of the slip stream against the controlsurfaces of the elevator, of

the ailerons and of the .rudder and this resistance is a function of theair speed of the aircraft and of the attitude of the aircraft. For

example, when the pilot pulls the stick back to execute a climbingmaneuver or pushes it forward to execute a diving maneuver the elevatoris moved out of its normal plane and therefore becomes engaged by theslip stream to a greater or less extent dependent upon the steepness ofthe intended climb or dive and the pressure of the slip stream upon theelevator surface reacts as a resistance to the movement of the elevatorwhich is transferred tothe stick as a resistance to be overcome by thepilot in moving the stick. Similarly, on a correctly executed turn, themovement of the rudder from its normal straight night position subjectsits surface to the pressure of the slip stream which reacts as aresistance to the movement of the rudder which is transferred to therudder pedals as a resistance to be overcome by the pilot in theirmovement and, the movement of the ailerons from their normal positionssubjects their surfaces to a change in pres- I" sure .from the slipstream which reacts as a resistance to their movement which istransferred to the aileron control wheel or stick as a resistance to beovercome by thev pilot in the movement of the wheel or stick. Also sincesome elevator control is also required on a correctly executed turn, thepilot will encounter some resistance to the forward or backward movementof the stick. At other times the movement of the controls does not meetas great resistance transmitted thereto by `pressures applied againstthe control surfaces. 'Ihe resistance to the movement of the controlsurfaces is a function of the air speed of the aircraft and in generalincreases as the air speed increases.

In the copending application of V. F. Bohman. R. C. Davis and C. E.Germanton, Serial No.

542.984 filed concurrently herewith apparatus is disclosed and describedfor applying loadings or resistances to the operation of the stick, theaileron control wheel and the rudder pedals of a-n aircraft trainersimulating the resistances to the movement of the similar controls of anactual aircraft under flight conditions.

14 Claims.

In night through rough air the pressures against the control surfaces ofthe elevator, rudder and ailerons will be more or less erratic resultingin a. transference of changing resistances to the movement of thecontrols and resulting in changing readings of the artificial horizonand bank indicator, altimeter, rate of climb indicator and rate of turnindicator on the instrument panel of the aircraft. An experienced pilotis able to manipulate the controls to overcome to a great extent theeilect of the rough air reactions upon the controls and to keep theaircraft in substantially steady flight.

It is the object of the present invention to simulate in an aircrafttrainer the change in loading or resistance to the movement of thecontrols of an actual aircraft subjected to flight in rough air and tosimulate the effect of rough air on the readings of the instruments ofthe trainer.

To attain this object the trainer is provided with mechanisms controlledby motor control circuits which apply loadings to the elevator controlstick, to the aileron control wheel and to the rudder control pedalswhich loadings are made to vary in accordance with the indicated airspeed. Motor control circiuts are provided for operating the rate ofturn indicator, and the artificial horizon and bank indicator on thepilot's instrument panel of the trainer and a further motor controlcircuit is provided for operating potentiometers which exercise controlover other motor control circuits of the trainer. In addition, and asthe main feature of novelty of the present invention, a motor controlcircuit is provided which promiscuously exercises control over theaforementioned motor control circuits to change the loadings on theelevator control stick, on the aileron control wheel and on the ruddercontrol pedals, to change the settings of the instruments and to changethe interacting effects between such motor control circuits of thetrainer as would be affected by the encountering of rough airconditions. This latter motor control circuit comprises two motor drivensequence switches of the general type disclosed in Patent No. 1,127,808granted February 9, 1915, to J. N. Reynolds and C. F. Baldwin. One ofthese switches is operable under the control of a start key through anydesired number of complete revolutions and upon the completion of eachrevolution to cause the second switch to advance one step, said secondswitch completing a single revolution in response to the completion ofeighteen revolutions of the lrst switch. Conjointly the twoswitches areeffective to apply alternating current of one phase or of the oppositephase for varying intervals and in a promiscuous manner to controlconductors connected to the aforementioned motorcontrol cir'-v cuitswhereby the motorsfof such circuits are operated in one or-the otherdirectionof rotation and to varying; extents to change the loadings, tochange the instrument readings and to vary the controls on othercircuits of the trainer.

second sequence switch having the contact closing cams I 29- to |43,inclusive. -Each of the se'- The start key together with three manuallyquence switches has eighteen contact closing positions each of whichpositions, may -provide different circuit combinations. It can bedesigned to stop in any one of these positions.v Cams |05 to |24,inclusive, and cams |30 to |43,v inclusive.

are so cut that in any contact closure position,

' indicated by the small numerals placed on either drives one of thesequence switches and which'- thereby controls the duration of eachcycle ofv operation of the rough air circuit.' 'Ihe two other rheostatsare connected in series with the alternating current supplies ofopposite phases p1 and p2 for regulating the potentialsA applied fromsuch sources to the rough air circuit.

` Although the switches of the rough air ,circuits have been illustratedasof thesequence switch type it is to be understood that other types'ofvswitches such, forvexample, as switches of the:

type which are advanced step by step under the control of steppingmagnets could be used.

The novel features of the invention are set forthin the appended claimsand the invention as to its organization and its mode of operation willbe best understood from a consideration of the following detaileddescription when read in connection with the accompanying drawings inwhich: Fig. 1 shows the rough air circuit embodying the presentinvention together with manual controls disclosed in the dot-dashrectangle in the upper right corner thereof;

Fig. 2 shows in the upper portion thereof the angle of attack motorcontrol circuit for operating potentiometers for controlling other motorcontrol circuits of a trainer and in the lower portion thereof the bankmotor control circuit' for operating potentiometers for controllingother motor control circuits and for operating the bank indicator of anartificial horizon instrument on the instrument panel of the trainer;

Fig. 3 shows in the upper portion thereof the rate of turn motor controlcircuit for operating potentiometers for controlling other motor controlcircuits and for operating a rate of turn indicator instrument on theinstrument panel of the trainer and in the lower portion thereof theschematic representation. of the elevator control yoke or stick, theaileron control wheel, the rudder control pedals and the loadingmechanisms therefor; and

Fig.'4 shows one of the control loading mechanisms indicatedschematically by the boxes in the lower portion of Fig. 3 and the motorcontrol circuit therefor.

Referring rst to Fig. 1, the motors MI and M2 are of the shunt fielddirect current type operable from the sources BI and B2 of directcurrent which sources and the sources B3, B4 and B5 shown in Figs. 2 and3, may be a common source. The motor Ml is started by the start key Klocated on the instructors desk and its speed is regulated by themanually operable rheostat RI. The shaft of the motor MI is connected bya coupling |I to the driving shaft of the reduction gear box |02, thedriven shaft of which is connected by a coupling |03 tothe driving shaftI 04 of the rst sequence switch having the contact closing cams to |24,inclusive.

The shaft of motor M2 is coupled by coupling to the driving shaft of thereduction gear box |26, the driven shaft of which is connected by acoupling |21 to the driving shaft |23 91, a

, any one of its regular stopping positions.

side of such cams, the contact becomes closed 5 degrees'vbefore theindicated position is reached and is again opened 5 degrees after theindicated position has been left. For example, referring to cam I|5 theposition marked 1 becomes closed 5 degrees earlier or in position 3A andbecomes `opened 5 degrees later or in position 11/4 and the positionmarked (i-71/2 becomes closed in position 5% and remains closed throughposition positions except when the switch is centered in The motors MI,M2, gear boxes |02 and |26 and the sequence switches may all be mountedon a suitable mounting plate.

The-rheostats RI, R2 and R3 and the start key K are located on theinstructors desk,

the key K controlling the starting circuit of the motor MI over thespeed controlling rheostat RI as previously described and alsocontrolling the application of current from phases p1 and p2 of analternating current source over the rheostats R2 and R3, cams |06 to||5, inclusive, and cams IIS to |24, inclusive, the rheostats R2 and R3being effective to adjust the potential'of the current of the twophases.

The motor control circuits disclosed in Figs. 2, 3 and 4 are of the typefully disclosed in the Patent No. 2,428,767 granted October 14, 1947, toW. P. Albert, R. C. Davis, R. H. Gumley and W. H. T. Holden. Each ofthese circuits is provided with a direct current motor such as motor M3which, through a gear reduction box 200, drives the shaft 20| on whichare mounted variable potentiometers (not shown) similar to PI forcontrolling other motor control circuits of the trainer, a balancingpotentiometer PI and a pair of limit switches LI and L2. The shaft ofthe bank motor control circuit shown in the lower portion of Fig. 2 andthe rate of turn motor control circuit shown in the upper portion ofFig. 3 also drive synchro-generators which are effective to drivesynchro-repeaters electrically associated therewith and mechanicallycoupled to indicating instruments on the instrument panel of the trainerand on the instrument panel of the instructors desk.

For controlling the motor of each control circuit whereby the motor maybe driven in either direction of rotation, two incoming signalamplifying tubes, such as VTI and VT2, two dual rectifier tubes, such asVT3 and VT4 and two gaslled tubes, such as VT5 and VTS and three relays,such as 2||, 2|2 and 2|3, are provided. The tubes VTI and VT2 areconnected in tandem and serve to receive an input potential and to applyit through the step-up transformer TI to the anodes of the rectifiertube VT3. The tube VT3 serves as a full wave rectifier to rectify the-Cam |29 is so cut that it is closed in all" is supplied from a source ofcommercial alternating current supply through the windings of powertransformer T2 and direct current for furnishing grid bias to thecontrol grids of tubes VT5 and VT3 is supplied from the alternatingcurrent source through the power transformer T2 and the dual rectifiertube VT4. Anode potential is supplied to tubes VTI and VT2 from thebattery B3 and 60-cycle alternating current potential is supplied to theanodes of tubes VT5 and VTI, the anode potential supplied to tube VT5being displaced 180 degrees in phase from the potential. supplied totube VT5.

The yoke or stick 350 of the trainer is disclosed schematically in thelower portion of Fig. 3 as rotatable around the shaft 35| as an axis andis operable, through the sector gear 352 secured to the lower end of theyoke and the gear 353 in mesh therewith, to rotate the shaft 354 tocontrol potentiometers (not disclosed) operable to control circuits ofthe trainer in response to the movement of the yoke in simulation of theoperation of the elevator of an aircraft. The shaft 354 is alsodisclosed as extending into a box 355 schematically representing theelevator loading or trimming mechanism and motor control circuittherefor fully disclosed in the copending application of Bohman et al.hereinbefore referred to.

The yoke 350 has at its upper end an aileron control wheel 358 whichthrough bevel gears (not shown) rotates the axial shaft 351 supportedwithin the tubular yoke and geared by the bevel gears 353 to the shaft35|. The clockwise or counter-clockwise rotation of wheel 350 is thuscommunicated to the shaft 35| and may be employed to controlpotentiometers (not disclosed) operable to control circuits of thetrainer in simulation of the operation of the ailerons of an aircraft.The shaft 35| is also disclosed as extending into a box 353schematically representing the aileron loading or trimming mechanism andmotor control circuit therefor fully disclosed in the copendingapplication of Bohman et al. hereinbefore referred to.

The rudder control pedals 350 and 353 are mounted on individual rockershafts 35| and 354. the shaft 35| having a downwardly extending arm 332and the shaft 354 having an upwardly extending arm 355, such arms beingconnected respectively by rods 355 and 361 with upwardly extending arms353 and 359 secured to the shaft 310. Thus the depression of the rightpedal 353 causes a clockwise rotation of the shaft 310 and thedepression of the left pedal` 352 causes a counter-clockwise rotation ofshaft 310. The clockwise or counter-clockwise rotation of shaft 310 maybe employed to control potentiometers (not disclosed) operable tocontrol circuits of the trainer in simulation of the operation of therudder of an aircraft. The shaft 310 is also disclosed as extending intoa box 31| schematically representing the rudder loading or trimmingmechanism and motor control circuit therefor fully disclosed in thecopending application of Bohman et al. hereinbefore referred to.

It is to be understood, however, that the control devices have beendisclosed schematically and y particular aircraft which the trainer isdesigned to simulate for training purposes.

'It will be assumed that the motor circuits disclosed in Figs. 2 and 3are in balance and that the motors M3, M4 and M5 thereof are therefore,

not operating; It will also be assumed that the instructor desires tointroduce a rough air condition into the simulated flight being flown bya pilot trainee to ascertain if the trainee reacts correctly to theimposed condition. It will be assumed further that the rheostats RI, R2and R3 at the instructors desk are adjusted into the positions disclosedand that to start the rough air circuit the instructor operates the keyK. With the key K operated the source of phase 1 alternating current isconnected through resistance |44, through rheostat R2, the middlecontacts of key K and over the right contact of cam I5 to all cams ofthe group |03 to H5, inclusive. The source of phase 2 alternatingcurrent is connected through resistance |45, through rheostat R3, theright contacts of key K and over the upper right contact of cam |24 toall cams of the group ||6 to |24, inclusive. and a circuit isestablished from ground through rheostat RI, over the left contacts ofkey K and through the rotor winding of motor M| to ground through thesource of direct current BI. With the stator winding of motor MIenergized from the source Bl, motor Ml now operates and through thereduction gear box |02 drives the shaft |04 of the first sequence switchat a slow speed determined by the speed of the motor as regulated by therheostat Rl. The rotation of the sequence switch shaft rotates the cams|05 to |24, inclusive.

The cams of the sequence switches may be in any one of their eighteencontact closure positions at the time they are started into rotation butfor clarifying the description it will be assumed that the cams of theupper sequence switch, which will hereinafter be identified by the motordesignation MI, are driven into the No. 1

40 contact position when the motor is started as just described and thatthe cams of the lower sequence switch, which will hereinafter beidentied by the motor designation M2, `are standing in the No. l contactposition. As switch Ml passes through positions 1 and 2 a circuit isestablished from the p2 source of alternating current connected to cam|1, over its up'per left contact closed in positions l through 2, overthe lower left contact of cam |'4|, the right contact of cam |43,through resistance |45, over conductor |41, through condenser 202 andrheostat 203 to ground and in parallel therewith to ground throughresistance` 312 and also in parauei therewith through resistance 313 tothe motor control oircuit associated with the elevator loading mechansm355.

The potential derived from the rheostat 203 is -applied throughresistance 204 to the control grid of tube VTI, is amplified thereby andby the tube VT2 and is then impressed through the transformer T| andthrough rectifier tube VT3 upon the control grid of tube VT5 and overthe lower secondary winding of transformer TI also upon the control gridof tube VT5. The signal potential incoming from the rough air circuitnow appears as potential of phase :p1 on the control grids of tubes VT5and VT5 and since the tube VT3 serves as a full wave rectifier thepotential applied to the grid of tube VT5 appears as a positivepotential. Alternating current from the source of phase o2, connectedbetween the termin-als 205 and 205, is at this time applied to the anodeof tube VT5 but, due to the fact that tube V T3 rectiiies both halfwaves of the signal potential, during one-half wave of the anodepotential of phase o2, both the grid and anode of tube VTS will bepositive and the tube will fire resulting in the transmission of animpulse of positive potential through the rotor winding of motor M3during each positive half wave of the anode current. The circuit throughthe rotor winding may be traced from terminal 20S over the anode-cathodepath through tube VTS, to the mid-point of the right secondary windingof transformer T2, through the rotor winding, over the back contact ofrelay 2|3 and returning to the ground terminal 200.

At the time that the-signal potential of phase el is impressed from thelower secondary winding of transformer TI upon the grid of tube VTS theanode of tube VTS is supplied with anode potential from the alternatingcurrent source of phase p1 connected between the terminals 206 and 201through the winding of reversing relay 2|| and tube VTS will thereforenre during each positive half wave of the anode potential in turncausing the operation of relay 2| 2. With relay 2|2 operated the statorwinding M of motor M3 is energized in a circuit extending from groundthrough the direct current source B3, over the outer right front contactof relay 2 I 2, through the stator winding of motor M3, over the innerrighi front contact of relay 2|2 and thence to ground over the normalcontact of limit switch LI. With the stator winding thus energized andthe rotor winding energized by the firing of tube VTS the motor M3 isoperated in one direction of rotation and through the gear box 200drives the shaft 20| in such a direction as to move the brush ofpotentiometer PI in a clockwise direction toward the left terminal ofits winding and Vto simil-arly advance the brushes of otherpotentiometers (not shown) which may be associated with the shaft 20|.

Current from a source connected between the terminals 208 and 209 of thesame frequency as the source connected between terminals 205, 206 and206, 201 is impressed upon the divided secondary winding of transformerT3 and, since the mid-point of the secondary winding is grounded,potential of phase p1 is applied over a circuit from ground, over thelower portion of such secondary winding, over the left portion of thewinding oi' potentiometer P| and the brush thereof, through resistance2| 0, condenser 202 and rheostat 203 to ground and at the same instantpotential of phase p2 is applied over a circuit from ground, over theupper portion of the secondary winding of transformer T3, over the rightportion of the winding of potentiometer PI' and the brush thereof,through resistance 2|0, condenser 202 and rheostat 203 to ground. Withthe brush of potentiometer PI engaging the midpoint of the potentiometerwinding the potentials of opposite phases'applied through resistance 2|0will balance each other but, as the brush moves toward the left terminalof the potentiometer winding under the control of motor M3 as justdescribed, potential of phase pl will increasingly predominate untilsuch potential balances the potential of phase p2 applied from the roughair circuit as previously described. As the unbalance decreases thepotential impressed upon the grid of tube VTS decreases resulting in thedecrease in the speed of motor M3 until it ilnally stops when thepotentiometer brush reaches a point where the potentials of oppositephase transmitted through the rheostat 203 are in balance and no signalpotential is impressed upon the grid of tube VTS. Shaft 20| has now beenset to a new angular position whereby the potentiometers associatedtherewith are instrumental in controlling other motor control circuitsof the trainer which should be affected by a rough air conditionaffecting the elevator of an aircraft.

Among the circuits which are thus ailected by the angle of attack motorcontrol circuit are the pitch motor control circuit indicated by the box3|| of Fig. 3, the altimeter motor control circuit indicated by box 3| 2of Fig. 3 and the rate of climb motor control circuit indicated by thebox 3| 3 of Fig. 3. These motor control circuits are similar to thosedisclosed herein and are controlled by potentiometers on the shaft ofthe angle of attack motor control circuit. The shaft of the angle of thepitch motor control circuit is instrumental in driving asynchro-generator which is electrically coupled with thesynchro-repeater SR3 which in turn go drives the horizon bar of theartificial horizon and bank indicator BI mounted on the pilotsinstrument panel. The horizon bar of a similar instrument mounted on theinstructors desk is also driven by a synchro-repeated oper- 35 ated inparallel with the synchro-repeater SR3.

The shaft of the altimeter motor control circuit is instrumental indriving a synchro-generator which is electrically coupled with thesynchro-repeater SR4 which in turn drives the altimeter ALT on thepilots instrument panel. Also an altimeter driven by a synchro-repeateroperated in parallel with the synchro-repeater SR4 is located on theinstructors desk.

The shaft of the rate of climb motor control circuit is instrumental indriving a synchro-generator which is electrically coupled with thesynchro-repeater SRS which in turn drives the rate of climb indicatorRCI on the pilots instrument panel. Also a rate of climb indicatordriven by 40 a synchro-repeater operated in parallel with thesynchro-repeater SRS is located on the instructors desk.

It will be recalled that potential was applied from the rough aircircuit through resistance 313 to the motor control circuit associatedwith the elevator loading mechanism 35S. As fully disclosed in thecopending application of Bohman et al., hereinbefore referred to themotor control circuit of the elevator loading mechanism is instrumentalin controlling such mechanism to alter the loading applied to shaft 354which change in loading is communicated through the gear 353 and sectorgear 352 to the yoke 350 and manifests itself to the trainee pilot asrequiring, for example, a greater eilort on his part to prevent a changein the position of the yoke.

One of the loading units, for example the unit for loading the yoke 350is disclosed in more detail in Fig. 4. If the pilot should pull back onthe yoke 350 or toward the right as viewed in Fig. 4, the movement ofthe yoke is transmitted through the cable 400 to the pulley 40| and thusto the shaft 402. The cable 400 for this purpose extends over idlerpulleys 403 and 404, over pulleys 40S and 406 journaled between the sidebars of a trim carriage 401 movable longitudinally with respect to theside members 408 and 409 of the mounting frame, and is wrapped aroundthe pulley 40|. Rotation of the shaft 402 is communicated through gears4|0 and 4|| whereby the loading pulley 4| 3 is rotated in acounter-clockwise direction and whereby through the gears 4| 4, 4|5 and4|6 the rotor of motor MS is rotated. As the pulley 4|3 rotates itexerts a pull on the upper cable 4|1 against the tension of the loadingspring 4|3 whereby a resistance to the turning of pulley 4|3 iscommunicated by the cable 400 to the pulley 4|0 and appears on the yoke350 as a load which the pilot must overcome to move the yoke. At thesame time due to the step-u-p ratio of the gear train including gears4|4, 4|! and 4|4, the rotor of motor M5 is rotated in the field oi suchmotor and since the rotor oi such motor is short-circuited asillustrated in the upper right` portion of Fig. 4, the motor serves as adynamic brake to exert a drag which is communicated through the gearing,pulleys and cable 40| to the yoke to give the pilot the usual feel ofthe yoke. This drag is, as before described, augmented by the resistancedue to the tensioning of spring 4|3.

To lessen the eilort required to pull the yoke 300 back, the pilot mayoperate the elevator trimming wheel 420. In an actual aircraft themovement of the trimming wheel operates the trimming tab on the elevatordownwardly so as to cause the elevator surface to move up and therebyforce the nose of the airplane to rise. In the trainer this operation issimulated by the rotation oi' the trimming wheel 42,0 in such adirection that the brush of the trimming p otentiometer P42 is movedcounter-clockwise to thereby increase the phase p1 potential appliedover the circuit from the brush of potentiometer P42 through resistance42|, condenser 422 and the winding of rheostat RI to ground whereby thisphase el potential overbalances the potential of phase p2 applied overthe brush of balancing potentiometer P4|, overv resistance 423, throughcondenser 422 and the winding of rheostat Ri to ground. Consequently apotential oi phase p1 derived from the rheostat Rl is applied to theinput grid of tube VTM, is amplifier by such tube and is applied as apotential of phase p1 upon the control grids of tubes VT44, VT4! andVTIB.

Since the potential applied to the grid of tube VT40 is out oi' phasewith the potential applied to the anode of such tube, tube VTIB does notbecome conducting and therefore relays 425 and 424 are not operated.Tubes VT44 and VT45 will, however, alternately fire to transmit positiveimpulses of current through the rotor circuit of motor M and, with thestator circuit of the motor completed from ground through the source ofdirect current B4I, through lamp resistance 420, over the inner rightback oi' relay 420, through the rotor circuit, over the outer right backcontact of relay 42| and over the normal contacts of limit switch L42 toground, the motor M3 rotates in such a direction as to rotate the leadscrew 421 in a counter-clockwise direction to thereby move the trimmingcarriage 401 of the elevator loading and trimming mechanism toward theright as viewed in Fig. 4.

As the carriage moves toward the right, the rack 423 rotates the gear423 and thereby rotates the brush of the balancing potentiometer P4| ina counter-clockwise direction. As the brush of Ipotentiometer P4| thusmoves, the potential of phase p2 is increased, thereby reducing theunbalance of the control circuit and the value of the signalingpotential which is applied to the grids of tubes VT44 and VT45. Themotor M8 thereupon slows down and when the brush of potentiometer P4| isso positioned that the potential of phase p2 applied thereover equalsthe potential of phase pl applied over the brush of potentiometer P42 nosignaling potential will appear on the grids of tubes VT44 and 10 VT44and the motor Ml will thereupon come to rest.

The movement of the yoke 350 toward the right through the cable 400causes the clockwise rotation of pulley 40| and consequently acounterclockwise rotation oi the loading pulley 4|3 which is restrainedin its rotation through the heavy pull exerted by the upper cable 4|1due to the loading spring 4|0. However, the movement of the trimmingcarriage 401 toward the right by the operation of motor M0 tends.through the cable 400, to cause pulley 40| to rotate in acounter-clockwise direction and consequently to cause the loading pulley4|3 to rotate in a clockwise direction. Thus two opposite rotationalforces are applied to the loading pulley 4I3, one by the movement of theyoke and the other by the operation of the trimming wheel 420. Thus ifthe trimming wheel is rotated sumciently the eil'ort required to movethe yoke to the position required may be materially reduced or indeedthe entire effort required to move the yoke may be supplied through thetrimming carriage in rponse to the operation of the trimming wheel.

Similar assistance for moving the elevator in the opposite direction maybe attained by the rotation of the elevator trimming wheel 420 in theopposite direction.

When potential is applied from the rough air circuit through resistance313 to the motor control circuit of Fig. .4, as previously described,the motor MB is caused to rotate in one or the other direction dependentupon the phase of the input potential to move the trimming carriage 401of the loading mechanism to thereby change the loading applied to theyoke 35| in the same manner as when potential is applied under thecontrol of the trimming potentiometer P42.

As switch MI passes through positions 1 and 2,

40 a circuit is also established from the phase p2 source of alternatingcurrent connected to cam |24, over the upper left contact of cam H3, thelower left contact of cam |3|, the right contact of cam |34 throughresistance |48, over conductor |49, through condenser 302 and rheostat303 to ground and in parallel therewith to ground through resistance 314and also in parallel therewith through resistance 315 to the motorcontrol circuit associated with the rudder loading mechanism 31|.

The potential derived from the rheostat 303 is applied throughresistance 304 to the control grid of the amplifier tube VT2|, isamplified thereby and by the tube VT22 and is then impressed through thetransformer T2| and through rectiiler tube VT23 upon the control grid oftube VT25 and potential from the lower right secondary winding oftransformer T2| is also impressed upon the control grid of tube VT23.Tubes VT25 and VTZS both become conducting and result in the operationof motor M5 in the manner previously described in connection with theoperation of motor M3 to Vdrive the shaft 33| through the reduction gearbox: 300 at a slow speed in a clockwise direction. The rotation of shaft30| results in the movement oi the brush of potentiometer P2| towardsthe left terminal of its winding and the similar movement of the brushesof other potentiometers (not shown) which may be associated with theshaft 30|. Shaft 30| also rotates the rotor of synchro-generator SG2resulting in the synchronous rotation of the rotor of synchro-repeaterSR2. The rotor of synchrorepeater SR2 being connected to the rate ofcurrent indicator RTI changes the reading of such indicator. When thebrush of the potentiometer P2| reaches a position in which thepredominating potential of phase:y p1 applied thereover, throughresistance 3|0l through condenser 302 and rheostat 303, balances thepotential applied through the rheostat from the rough air circuit, themotor M comes to rest. 'I'he shaft 30| has now been set to a new angularposition whereby potentiometers associated therewith are instrumental incontrolling other motor control circuits of the trainer which should beaffected by a rough air condition aiecting the rudder of an aircraft.

It is to be understood that in addition to the rate of turn indicatorRTI mounted on the pilots instrument panel a duplicate of suchinstrument driven by a synchro-repeater connected in parallel with thesynchro-repeater SR2 would be mounted on the instructors desk forobservation by the instructor.

It will be recalled that potential was applied from the rough aircircuit through resistance 315 to the motor control circuit associatedwith the rudder loading mechanism 31|. As fully described in theapplication of Bohman et al. hereinbefore referred to, the motor controlcircuit of the rudder loading mechanism is instrumental in controllingsuch mechanism to alter the loading applied to shaft 310 which change inloading is communicated to the rudder pedals 360 and 363 and manifestsitself to the trainee pilot as requiring, for example, a greater eii'orton his part to prevent a change in the incident position of the rudderpedals. The rudder loading mechanism is of substantially the sameconstruction as the elevator loading mechanism shown in detail in Fig.4.

As switch M| passes through positions 1 to 31/2, inclusive, a circuit isalso established from the phase p1 source of alternating currentconnected to cam ||5, over the upper left contact of cam |06, over thelower left contact of cam |31, the lowerI right contact of cam |36,through resistance |50, over .conductor |5|, through condenser 252 andrheostat 253 to ground and in parallel therewith to ground throughresistance 316 and also in parallel therewith through resistance 311 tothe motor control circuit associated with the aileron loading mechanism359. The aileron loading mechanism is of substantially the sameconstruction as the elevator loading mechanism shown in detail in Fig.4.

The potential derived from the rheostat 253 is applied throughresistance 254 to the control grid of the amplier tube VT||, isamplified thereby and by the tube VT|2 and is then impressed through thetransformer Til and through rectifier tube VT|3 upon the control grid oftube VIfl5, and from the lower secondary winding of transformer Tll uponthe control grid of tube VT|6. In the manner previously described tubeVT|5 will become conducting during each interval that positive potentialis applied to its anode from the phase p1 source of alternating currentconnected between the terminals 255 and 256 and will establish the rotorcircuit of motor M4. Since, however. the potential applied to the inputcircuitv of tube VT|| has resulted in the application of potential tothe control grid of tube VT|6 which is out of phase with the phase p1source of anode current connected between the terminals 256 and 251 andsupplied to the anode of tube VTIG, tube VT|6 does not operate andrelays 26| and 262 remain unoperated. The circuit through the statorwinding of motor M4 may therefore be traced from ground through thesource of direct current B4, over the inner right back contact of relay262, through the stator winding of motor M4, over the outer right backcontact of relay 26| and over the normal contact of limit switchy L|2 toground.

Withits stator and rotor windings thus energized motor M4 is operated ina direction of rotation to drive the shaft through the reduction gearbox 260 in a counter-clockwise direction. The rotation of shaft 25|results in the movement of the brush of potentiometer P|| toward theright terminal of its winding and the similar movement of the brushes ofother potentiometers (not shown) which may be associated with the shaft25|. As the -brush moves toward the right terminal of its windingpotential of phase p2 applied thereover from the upper portion of thesecondary winding of transformer T|3, through resistance 260, condenser252 and rheostate 253 increasingly predominates until it balances thepotential of phase @l applied through the rheostate 253 from the roughair circuit, at which time the motor M4 will come to rest. The shaft 25|has now been set to a new angular position whereby potentiometersassociated therewith are instrumental in controlling other motor controlcircuits of the trainer which should -be aected by a rough air conditionaffecting the ailerons of an aircraft.

The shaft 25| also rotates the rotor of synchrogenerator SGI resultingin the synchronous rotation of the rotor of synchro-repeater SRI. Therotor of synchro-repeater SRI being connected to the bank indicator andartificial horizon indicator BI mounted on the pilots instrument panel,changes the reading of such bank indicator. It is to be understood thata similar indicator driven by a synchro-repeater connected in parallelwith the synchro-repeater SRI would be mounted on the instructors deskfor observation by the instructor.

As the switch MI passes through positions 13 to 141/2, inclusive, acircuit is established from the phase 1p1 source of alternating currentconnected to cam |5, over the upper left contact of cam |01, over thelower left contact of cam |3I, the right contact of cam |34, throughresistance |48 and over conductor |49 to the rate of turn motor controlcircuit and to the motor control circuit associated with the rudderloading mechanisxn 31|. Since potential of phase p1 is now applied tothese circuits the motors thereof are controlled to operate in theopposite direction of rotation from that previously described or in themanner'described in connection with the operation of the motor M3 oftheangle of attack motor control circuit, resulting in a reverse change inthe loading applied to the rudder pedals 360 and 363 and a reversesetting of the rate of turn indicators RTI on the pilots and instructorsinstrument panels.

As the switch MI passes through positions 15 to 171/2, inclusive, acircuit is established from the phase p2 source of alternating currentconnected to cam |24, over the upper left contact of cam |6, over thelower left contact of cam |3|, the right contact of cam |34, throughresistance |40 and over conductor |49 to the rate of turn motor controlcircuit and to the motor control circuit associated with the rudderloading mechanism 31|. Since potential of phase p2 is now applied tothese circuits the motors thereof are controlled to operate in theopposite direction of rotation t0 that just described resulting in areverse change -in the loading applied to the rudder pedals and overconductor |41 to the angle of attack motor l0 control circuit and to themotor control circuit associated with the elevator loading mechanism855. Since .potential of phase o1 is now applied to these circuits themotors thereof are controlled to operate in the opposite direction ofrotation from that previously described or in the manner described inconnection with the motor M4 of the bank motor control circuit,resulting in a reverse change in the loading applied to the yoke andreverse settings of the horizon bars of the artincial horizon and bankindicators, reverse settings of the rate of climb indicators and reversesettings oi the altimeters on the pilot's and instructors instrumentpanels.

As the switch MI passes through position |1 a circuit is establishedfrom ground over the lower leit and upper right contacts o! cam |55,through the winding of relay |52 to battery and ground, whereupon relay|52 operates and locks in a circuit through its winding over its uppercontact,

over the right contact of cam |35 of sequence Y switch M2, closed inposition 1, to ground over the lower contact of cam |29 until switch M2has been Aadvanced out of position 1. Relay |52 also establishes acircuit frombattery through the winding of relay |53, over the lowercontact or relay |52, over the lower right and upper left contacts o!cam |05, over the left contact oi! cam |30 to ground over the lowercontact oi! cam |22 when switchMl passes through position 18%. Relay |53thereupon operates and establishes the circuit of motor M2 which,through the gear box |25, rotates the shaft |28 of the sequence switchdriven thereby. As the cam |29 driven by the shaft |28 rotates, itcloses a holding circuit for relay |53 until the cam |29 is moved to aposition indicative that the cams of the switch have been centered inthe stopping position 2. Relay |53 then releases and the rotation of thesequence switch shaft is arrested. As cam moves out of its No. 1 contactposition into its No. 2 contact position, the locking circuit of relay|52 is opened and relay |52 releases.

With switch M2 now in position 2, the rotation of`switch Mi throughanother complete revolution. again establishes circuits from the phaseo1 and phase p2 sources of alternating current to conductors |41, |49and |5| and when it again reaches position I1 relay |52 is againoperated followed by the operation of relay |53 when switch Mi reachesposition 18% and the ad- Vance of switch M2 into position 3 iscontrolled in the manner just described. With sequence switch M2 now inposition 3, the rotation of switch MI through another completerevolution again establishes circuits from the phase p1 and phase p2sources of alternating current to conductors |41, l and |5i. In thismanner as switch MI makes successive revolutions, switch M2 is advancedfrom position to position until the instructor opens the start key K.

The following table indicates the controls exercised over the elevator,rudder and aileron loading mechanisms and' the controls exercised overtbe anale o! attack, rate of turn and bank motor control circuits duringone complete cycling oi the switches MI and M12.

Politis!! Pltidi Phare o| Con- Motor Ciraiit siam Cun'mt [uw Cou 1 IK 11 3 1 1+ I 1 134-14 1 15+17 1 +18 1 2 5 2 #+15 14+1 2 +18 1H 5 '1+5 l154-18 I 16v-H8 i 5+ 7 4 5+ 7 4 11+13 4 1I+13M 4 15+17 3+ 5 5 3+ 5 5 6+7K 5 H12 5 i+1() 5 14+15 5 14+17 g 4+ 5 5 4+ 5 g 1i g 1mml of A si zsers-Mm- 1s+i1x 1 Bank. 11H-16 7 Angle 0i Attack. 17+18 Rats 0l Turn.

4+ 8 llgk of Attack.

s msm i 14+1s s Bmx.

11H-18 s Bate ci Turn.

3+ 3 9 Angle of Attack. 3+ 3 9 Bank. 5;; 3 demi Am" 1a+14 9 Angie' ofAttack. 11H-l 13 Rate o| Turn.

in? Angllgooi Attack. n+gx itl am oi'rum.

3+ 7 11 Bank. l Ani;B le o( Attack. l MMI'MM 1HE Angie' or Amex.

3+ 3 12 Do. 4+. 8 12 Rate 0| Turn. 114-14 12 Bank. 11+14 12 Rate 0f Tum.15+1s 12 Do. 17+1B 12 D0.

18 l2 Bank. 18% 13 H AMR. um iH-11 13 121-14 13 .d0.-- 11H-gx Rudder s+454 14 si do 4+ 8 14 il Aileron Bank. H Elevator Anggf Attack.

0 164-2 p2 Rudder Rats o( Turn.

4+ l5 o2 Aileron Bank. 6+l0 15 #2 Elevator Angle of Attack. 9+10} 15 alAileron Bank. larg i: si .do Do. 3+ 4 16 2 .do Do. (i4-lg al ElevatorAngle oi Attack.

7 17 D0. 10+l4} 17 Bank. s: i; 1s is 1+ 5gg 18 D0.

7 15 #111k d Attack.

Position Position Phase of Loading Con- Motor Circuit o' Eiltch ofsnchCurrent trol f Controlled` 7 18 951 Rudder Rate of Turn 8+ 9% 18 t2Aileron 8+10 18 4:2 Elevator .Angle of Attack Q-l-lll 18 2 Rudder Rateof Turn. 13+14 18 2 Elevator Angle of Attack. 11H-16 18 dl ---.do Do.

If it should be considered desirable for any reason to omit the controlof any one of the loading mechanisms from the rough air motor controlcircuit the connection from the control conductor |41, |49 or I5I tosuch mechanism may be omitted. -For example, if it should be desired toomit the control of the elevator loading mechanism 355 from the roughair circuit, the connection from conductor |41 through resistance 313would be omitted.

What is claimed is:

1. In an aircraft trainer, a control member, means for applying a loadto said control member in simulation of its operation under actualflight conditions, instruments for indicating different nightconditions, means for operating said instruments. an instructors desk,motor-driven switching'means for variably controlling said instrumentoperating means and said loading means to simulate the eect on thesimilar instruments of an aircraft and the effect on the response of thecontrol of an aircraft when rough air conditions are encountered, andmeans at said desk for controlling said latter means.

2. In an aircraft trainer, an elevator control yoke, means for applyinga load to said yoke in simulation of its operation under actual nightconditions, instruments for indicating different night conditions, meansfor operating said instruments, an instructors desk, motor-drivenswitching means for variably controlling said instrument operating meansand said loading means to simulate the effect on the similar instrumentsof an aircraft and the eiect on the response of the yoke of an aircraftwhen rough air conditions are encountered, and means at Said desk forcontrolling said latter means.

3. In an aircraft trainer, aileron control means, means for applying aload to said control means in simulation of its operation under actualnight conditions, instruments for indicating different night conditions,means for operating said instruments, an 'instructors desk, motor-drivenswitching means for variably controlling said instrument operating meansand said loading means to simulate the effect on the similar instrumentsof an aircraft and the eiect on the response of the control means of anaircraft when rough air conditions are encountered, and means at saiddesk for controlling said latter means.

4. In an aircraft trainer, rudder control pedals, means for applying aload to said pedals Vin simulation of their operation under actual fightconditions, instruments for indicating different night conditions, meansfor operating said instruments, an instructors desk, motor-drivenswitching means for variably controlling Said instrument operating meansand said loading means to simulate the effect on the similar instrumentsof an aircraft and the effect on the response of the rudder controlpedals of an aircraft when rough air conditions are encountered, andmeans at said desk for controlling said latter means.

5. In an aircraft trainer, an elevator control 16 yoke, an aileroncontrol wheel, rudder control pedals, means for applying loads to saidcontrol wheel and to said rudder pedals in simulation of their operationunder actual night conditions, instruments for indicating differentnight conditions, means for operating said instruments, an instructorsdesk, motor-driven switching means for variably controlling saidinstrument operating means and said loading means to simulate the en'ecton the similar instruments of an aircraft and the effect on the responseof the aileron control wheel and rudder control pedals of an aircraftwhen rough air conditions are encountered, and means at said desk forcontrolling said latter means.

6. In an aircraft trainer, an elevator control yoke, an aileron controlWheel, rudder control pedals, means for applying loads to said controlsin simulation of their operation under actual night conditions,instruments for indicating different night conditions, means foroperating said instruments, an instructors desk, motor-driven switchingmeans for variably controlling said instrument operating means and saidloading means to simulate the effect of the similar instruments of anaircraft and the effect on the response of the controls of an aircraftwhen rough air conditions are encountered, and means at said desk forcontrolling said latter means.

7. In an aircraft trainer, an elevator control yoke, an aileron controlwheel, rudder control pedals, means for applying loads to said controlwheel and to said rudder pedals in simulation of their operation underactual night conditions,

, an altimeter, a rate of climb indicator, a rate 0f turn indicator andan artincial horizon and bank indicator for indicating different nightconditions, means for operating said instruments, an instructors desk,motor-driven switching means for variably controlling said instrumentoperating means and said loading means to simulate the effect on thesimilar instruments of an aircraft and the effect on the response of thecontrols of an aircraft when rough air conditions are encountered, andmeans at said desk for controlling said latter means.

8. In an aircraft trainer, an elevator control yoke, an aileron controlwheel, rudder control pedals, means for applying loads to said controlsin simulation of their operation under actual night conditions, analtimeter, a rate of climb indicator, a rate of turn indicator, and anartincial horizon and bank indicator for indicating different nightconditions, means for operating said instruments, an instructors desk,motordriven switching means for variably controlling said instrumentoperating means and said loading means to simulate the effect on thesimilar instruments of an aircraft and the effect on the response of thecontrols of an aircraft when rough air conditions are encountered, andmeans at said desk for controlling said latter means.

9. In an aircraft trainer, an elevator control yoke, an aileron controlwheel, rudder control pedals, means for applying loads to said controlsin simulation of their operation under actual night conditions, an angleof attack motor control circuit, a bank motor control circuit, a rate ofturn motor control circuit, instruments for indicating different nightconditions controlled by said motor control circuits,v an instructorsdesk, motor-driven switching means for variably controlling saidcircuits and said loading means to simulate the effect on the similarinstruments of an aircraft and the effect on the response of 17 thecontrols ofan aircraft when rough air conditions are encountered, andmeans at said desk for controlling said latter means.

10. In an aircraft trainer, an elevator control yoke, an aileron controlwheel, rudder control pedals, means for applying loads to said controlsin simulation of their operation under actual iiight conditions, analtimeter, a rate of climb indicator, a rate of turn indicator, a bankindicator, and an artificial horizon instrument for indicating differentflight conditions, an angle of attack motor control circuit forcontrolling said altimeter, rate of climb indicator and artiiicialhorizon instrument, a bank motor control circuit for controlling saidbank indicator, a rate of turn motor control circuit for controllingsaid rate of turn indicator, an instructors desk, motor-driven switchingmeans for variably controlling said circuits and said loading means tosimulate the effect on the similar instruments of an aircraft and theeffect on the response of the controls of an aircraft when rough airconditions are encountered, and means at said desk for controlling saidlatter means.

11. In an aircraft trainer, an elevator control yoke, an aileron controlwheel, rudder control pedals, means for applying loads to said controlsin simulation of their operation under actual flight conditions,instruments for indicating different flight conditions, sources ofpotental, a first switch, a second switch, means for advancing saidsecond switch through one cycle in response to the completion of aplurality of cycles by said first switch, a plurality of circuit pathsconjointly established by said switches in the different positionsthereof, an instructors desk, and Imeans controlled from said desk forcausing the cycling of said switches to apply potentials fromsaidsources over said circuit paths to variably control said instrumentsand said loading means to simulate the effect on the similar instrumentsof an aircraft and the effect of the response of the controls of anaircraft when rough air conditions are encountered.

l2. In an aircraft trainer, an elevator control yoke, .an aileroncontrol wheel, rudder control pedals, means for applying loads to saidcontrols in simulation of their operation under actual night conditions,instruments for indicating different flight conditions, sources ofpotential, a first switch, a second switch, means for advancing saidsecond switch through one cycle in response to the completion of aplurality of cycles by said rst switch, a plurality of control pathsconjointly established by said switches in the different positionsthereof, an instructors desk, means controlled from said desk forcausing the cycling of said switches to apply potentials from saidsources over said circuit paths to variably control said instruments andsaid loading means to simulate the effect on the similar instruments ofan aircraft and the effect on the response of the controls of anaircraft when rough air conditions are encountered, and means at theinstructors desk for varying the speed at which said first switch isoperated to vary the duration of the intervals during which saidpotentials are applied and thereby the duration of the rough aireffects.

13. In an aircraft trainer, an elevator control yoke, an aileron controlwheel, rudder control pedals, means for applying loads to said controlsin simulation of their operation under actual flight conditions,instruments for indicating different flight conditions, sources ofpotential, a first switch, a second switch, means for advancing saidsecond switch through one cycle in response to the completion of aplurality of cycles by said first-switch, a plurality of circuit pathsconjointly established by said switches in the different positionsthereof, an instructors desk, means controlled from said desk foi`causing the cycling of said switches to apply potentials from saidsources over said circuit paths to variably control said instruments andsaid loading means to simulate the effect on the similar instruments ofan aircraft and the effect on the response of the controls of anaircraft when rough air conditions are encountered, means at theinstructorss desk for varying the speed at which said rst switch isoperated to vary the duration of the intervals during which thepotentials are applied and thereby the duration of the rough aireffects, and rheostats at said desk for varying said potentials tothereby vary the intensity of the rough air effects.

14. In an aircraft trainer, an elevator control yoke, an aileron controlwheel, rudder control pedals, means for applying loads to said controlsin simulation of their operation under actual iiight conditions,instruments for indicating different flight conditions, sources ofpotential, a first motor driven switch, a second motor switch operablethrough one cycle in response to the completion of a plurality of cyclesby said rst switch, a plurality of circuit paths conjointly establishedby said switches in different contact closing positions thereof, aninstructors desk, a start key at said desk for establishing an operatingcircuit for the motor of said first switch and for connecting saidsources of potential to contacts of said switches whereby said switchesare caused to cycle and apply potentials from said sources over saidcircuit paths to variably control said instruments and said loadingmeans to simulate the effect on the similar instruments of an aircraftand the effect on the response of the controls of an aircraft when roughair conditions are encountered, a rheostat at said desk in the motorcircuit of said first switch to vary the speed at which said firstswitch is operated to vary the duration of the intervals during whichsaid potentials are applied and thereby the duration of the rough `aireffects, arid rheostats at said desk for varying said potentials tothereby vary the intensity of the rough air effects.

CHARLES E. GERMANTON.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,393,456 Ruggles Oct. 11, 19211,865,828 Buckley June 5, 1932 1,960,350 Shackleton May 29, 19342,099,857 Link Nov. 23, 1937 2,155,346 Davis Apr. 18, 1939 2,164,412Koster July 4, 1939 2,306,429 Edwards Dec. 29, 1942 2,336,711 BarberDec, 14, 1943 2,366,603 Dehrnel Jan. 2, 1940 FOREIGN PATENTS NumberCountry Date 548,093 Great Britain 1942

